Margaret Thatcher's days of fighting elections may be long over, but in theatreland her legacy is still being put to the popular vote.

Hours after the announcement of her death on Monday at the age of 87, the producers of Billy Elliot: the Musical took the highly unusual step of asking audience members to vote on whether a song calling for her death should be performed or left out, as a mark of respect.

The musical – set in County Durham during the miners' strike of 1984–85 – prominently features a song by Elton John, Merry Christmas, Maggie Thatcher, which includes the line: "We'll all celebrate today 'cause it's one day closer to your death."

A source close to the production told the Telegraph: "It was taken seriously and debated and finally decided that it would be best to put it to a democratic vote to the audience."

Following a "near-unanimous verdict", in which only three people voted against its inclusion, the number was performed as usual at the Victoria Palace theatre.

Billy Elliot was not the only West End show to feel the impact of Thatcher's death. At the Gielgud theatre on Shaftesbury Avenue Peter Morgan's play The Audience, which features a lengthy scene in which Thatcher – played by Haydn Gwynne – meets the Queen, also went ahead unchanged, though the playwright personally introduced the play before the performance.

Morgan introduced himself and thanked the audience for coming, before saying: "Today one of the great figures of postwar British political life and the longest serving prime minister of the 20th century, and therefore the participant of the greatest number of the audiences with the queen, died. I just wanted to mark that occasion this evening with all of you."

The play, which stars Helen Mirren as the monarch, features a number of the prime ministers to have served during her reign, including Thatcher.